An example of a structure for rotating keys in an electronic keyboard apparatus is a structure in which a thin plate having flexibility is horizontally arranged (e.g., Japanese Patent Application Laid-Open No. 2008-191650). When the thin plate is bent and deformed, the keys can be rotated in an up-and-down direction. Japanese Patent Application Laid-Open No. 2008-191650 further discloses a structure capable of permitting movement in a direction in which the keys are arranged by further using a thin plate vertically arranged together and connecting the thin plate vertically arranged in series with the thin plate horizontally arranged.